Spitfire 1500 not starting

[Dannyb]

I'm getting a good spark and fuel. It will try to fire but only when turning on the starter. 

So I have looked at the ballast wire. Disconnected it from the coil and with ignition off I get a reading of 4 ohms between it and earth. If I turn on the ignition I'm getting 12v supply. 

Have I got a ignition wiring problem or am I confusing myself.

I also tried a 12v feed from battery to the coil and removed the ballast wire and still would not start. I know its a 6v coil but should be OK for a minute or so.. 

Could it be the ignition switch? 

Any ideas would be appreciated. 

Danny

 

[RobPearce]

If it doesn't start when you feed battery directly to coil then it's not (just) an ignition switch problem or a ballast resistor problem. My guess is coil, points or condenser (if still traditional) or the electronic ignition module if you have one, or the fuel.

And I'd say you're not getting a "good spark" and fuel - you're getting either a weak spark that just doesn't immediately look weak with an eyeball check, or a mixture that's too far out, or your fuel is too old.

But I'm not quite clear what you mean by "try to fire but only ... on the starter". Does it actually fire up and run until you release the key, or does it just cough and splutter so that releasing the key stops the engine turning (so of course it stops trying to start)?

[Dannyb]

Hi Rob. It's only the odd fire, one or two the most.

I have taken the Accuspark of and fitted set of points. I notice when the ign is on and I break the points there's not much of a spark. I'm sure if my memory is right when I last had a set of points fitted I got more of a spark.  The spark at the points is hardly noticeable. 

I may rig up a spare coil and bypass all the ignition system. 

Danny

[Dannyb]

OK we are up and running now. This has been very strange. I have checked everything, valve timing. Static timing, spark ugs, leads,carbs.. In the end I checked the voltage on the ballast wire under load, it was only 4v. Can't understand why it wouldn't start with 12v supplied straight to it unless it was flooded. Anyway I have now fitted a lucas 12v sports coil and bypassed the ballast wire and all seems good. Unable to road test at the moment with this weather. 

The other strange thing it the fuel and temp gauge stopped working which is because the solid state voltage regulator is fried, its only putting out 2v. Fitted the original and the gauges work, so ordered a new solid state one. 

Seems strange that both these problems are all linked to the ignition wires.

Its booked in for a rolling road tune at the end of the month. 

Danny

 

 

 

[RobPearce]

A possible cause of the 4V reading that would also result in not starting with the ballast bypassed... would be a short in the coil primary. Reduces the magnetic field achieved and thus the HT energy for the spark, but also exhibits a reduced DC resistance and hence lower ballast output voltage.

Failure of solid state voltage regulators is so common that for it to happen along with something else is just a coincidence, I suspect.

[Dannyb]

Yesterday I dug out a good spare ballast coil from my sparesand rigged it up to the ballast wire. It confirmed 4v from the ballast wire under load. 

I wondering if some sort of short could have happened on the ignition circuit which is not fused could have affected the solid state voltage regulator and ballast wire. 

Danny